The present invention relates generally to devices for tracking the gaze of the human eye, and more particularly to an optical device for tracking eye movement by analysis of the reflection off the eye of an infrared (IR) beam.
Existing systems for tracking eye movement include electronystagmography methods and magnetic tracking of scleral induction coils imbedded in annuli attached to the eye with a contact lens. These methods are invasive and of limited accuracy and generally require careful subject preparation, substantially constant recorder calibration and a controlled laboratory environment. Another system uses differences in IR light reflected from the iris and sclera as detected by a pair of photodetectors, which differences are linearly related to eye rotation over a range of about .+-.25.degree.. This system can accurately track the limbus horizontally but not vertically, since the limbus is partially occluded by the eyelid, and requires apparatus the placement of which partially obstructs the vision of the subject.
It is a principal object of the invention to provide a method and apparatus for real time, non-invasive and nonoccluding measurement of eye position.
It is a further object of the invention to provide two dimensional tracking of the human eye, including indication of horizontal and vertical position of the eye.
It is a further object of the invention to provide compact, lightweight and portable apparatus for eye tracking.
It is another object of the invention to provide means for fixation monitoring in field-of-vision testing.
It is yet another object of the invention to provide means for tracking both eyes in stereoscopic vision in tracking the fixation point of a subject's gaze in a three-dimensional volume of space.
It is yet another object of the invention to provide means for computer cursor positioning using eye movement.
It is yet another object of the invention to provide means for two-dimensional eye gaze control of a cursor in a computer display.
It is yet another object of the invention to provide means for three-dimensional control of a cursor in a stereoscopic computer display.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.